MP2459 0.5A, 55V, 480kHz Step-Down Converter in a TSOT23-6 The Future of Analog IC Technology DESCRIPTION FEATURES The MP2459 is a monolithic, step-down, switchmode converter with a built-in power MOSFET. It achieves a 0.5A peak-output current over a wide input supply range with excellent load and line regulation. Current-mode operation provides a fast transient response and eases loop stabilization. Fault condition protections include cycle-by-cycle current limiting and thermal shutdown. • • • • • • • • • • • The MP2459 requires a minimal number of readily-available external components. The MP2459 is available in a TSOT23-6 package. 0.5A Peak Output Current 1Ω Internal Power MOSFET Stable with Low-ESR Ceramic Output Capacitors Up to 90% Efficiency 0.1µA Shutdown Mode Fixed 480kHz Frequency Thermal Shutdown Cycle-by-Cycle Over-Current Protection Wide 4.5V-to-55V Operating Input Range Output Adjustable from 0.81V to 0.95*VIN Available in a TSOT23-6 Package APPLICATIONS • • • • • Power Meters Distributed Power Systems Battery Chargers Pre-Regulator for Linear Regulators WLED Drivers All MPS parts are lead-free and adhere to the RoHS directive. For MPS green status, please visit MPS website under Products, Quality Assurance page. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION 100 VIN BS T IN 90 MP2459 80 L1 GND U1 VOU T SW D1 EN EN 70 60 FB GND 50 40 30 0.0 MP2459 Rev. 1.0 3/4/2013 0.1 0.2 0.3 0.4 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 0.5 0.6 1 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 ORDERING INFORMATION Part Number* Package TSOT23-6 MP2459GJ Top Marking AEQ * For Tape & Reel, add suffix –Z (eg. M2459GJ–Z); PACKAGE REFERENCE TOP VIEW BST 1 6 SW GND 2 5 IN FB 3 4 EN ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Supply Voltage VIN ........................ −0.3V to 60V VSW ........................................ −0.3V to VIN+0.3V VBS .......................................................VSW + 6V All Other Pins ................................ −0.3V to +6V Continuous Power Dissipation (TA = +25°C) (2) TSOT23-6 .............................................. 0.568W Junction Temperature .............................. 150°C Lead Temperature ................................... 260°C Storage Temperature .............. −65°C to +150°C TSOT23-6 .............................. 220 ... 110 °C/W Recommended Operating Conditions (3) Supply Voltage VIN .......................... 4.5V to 55V Output Voltage VOUT............... 0.81V to 0.95×VIN Operating Junction Temp. ....... −40°C to +125°C MP2459 Rev. 1.0 3/4/2013 (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ(MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD(MAX)=(TJ(MAX)TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device function is not guaranteed outside of the recommended operating conditions. 4) Measured on JESD51-7, 4-layer PCB.. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 2 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 ELECTRICAL CHARACTERISTICS VIN = 12V, TA = +25°C, unless otherwise noted. Parameters Symbol Condition Feedback Voltage VFB 4.5V ≤ VIN ≤ 55V Feedback Current IFB VFB = 0.85V Switch-On Resistance RDS(ON) Switch Leakage ISW_LKG Typ Max Units 0.792 0.812 0.832 V 0.1 µA 1 VEN = 0V, VSW = 0V Current Limit ILIM Oscillator Frequency fSW Foldback Frequency fSW_F VFB = 0V Maximum Duty Cycle DMAX VFB = 0.6V Minimum ON-Time Min VFB = 0.6V Ω 1 µA 1.0 1.25 1.5 A 380 480 580 kHz 90 τON 150 kHz 93.5 % 100 ns Under-Voltage Lockout Threshold, Rising VUVLO_R 2.9 3.3 3.7 V Under-Voltage Lockout Threshold, Falling VUVLO_F 2.65 3.05 3.45 V Under-Voltage Lockout Threshold, Hysteresis VUVLO_HYS 250 mV EN Threshold, Rising VEN_R 1.35 V EN Threshold, Falling VEN_F 1.17 V VEN_HYS 180 mV EN Threshold, Hysteresis VEN = 2V 3.1 VEN = 0V 0.1 IS VEN = 0V 0.1 1.0 µA IQ VEN = 2V, VFB = 1V 0.73 0.85 mA EN Input Current IEN Supply Current (Shutdown) Supply Current (Quiescent) Thermal Shutdown Thermal Shutdown Hysteresis MP2459 Rev. 1.0 3/4/2013 µA TSD 165 °C TSD_HYS 20 °C www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 3 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 TYPICAL CHARACTERISTICS VIN=12V, VOUT=5V, IOUT=0.5A, L=15µH, TA=25°C, unless otherwise noted. 80 180 60 120 40 80 180 60 120 40 60 20 0 0 -20 -60 -40 -80 100 1000 0.9 0 0 -20 -60 -180 -80 10000 1000001000000 100 70 EN 55022 Voltage on M ains QP EN 55022 Voltage on M ains AV 40 30 20 10 0 150k 300 MP2459 Rev. 1.0 3/4/2013 8001M 2M 3M 5M 1000 -180 0.3 5 10000 1000001000000 15 25 35 45 55 65 Radiation EMI 80 50 0.7 -120 0.5 -60 Conduction EMI 60 1.1 60 20 -40 -120 -60 1.3 810M 20M 30M 60 55 50 45 40 35 30 25 20 15 10 5 0 30M EN 55022 Electric Field Strength 3 m QP 5060 80100M 200 300 400500 8001G www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 4 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 TYPICAL PERFORMANCE CHARACTERISTICS VIN=12V, VOUT=5V, L=22µH, TA=25°C, unless otherwise noted. Efficiency vs. Load Load Regulation Line Regulation IOUT =0.5A 100 90 80 70 60 50 40 30 0.0 0.2 0.4 0.6 0.8 1.0 2.0 1.6 1.2 0.8 0.4 0.0 -0.4 -0.8 -1.2 -1.6 -2.0 0.00.10.20.30.40.50.60.70.8 LOAD CURRENT ( A ) 2.0 1.6 1.2 0.8 0.4 0.0 -0.4 -0.8 -1.2 -1.6 -2.0 6 LOAD CURRENT ( A ) 16 26 36 46 56 INPUT VOLTAG ( V ) Load Regulation V OUT =3.3V 90 80 70 60 50 40 30 0.0 2.0 1.6 1.2 0.8 0.4 0.0 -0.4 -0.8 -1.2 -1.6 -2.0 0.00.10.20.30.40.50.60.70.8 LINE REGULATION ( % ) 100 0.2 0.4 0.6 0.8 1.0 LOAD CURRENT ( A ) 2.0 1.6 1.2 0.8 0.4 0.0 -0.4 -0.8 -1.2 -1.6 -2.0 6 LOAD CURRENT ( A ) 600 850 1.7 560 830 1.4 520 810 1.1 480 790 0.8 440 770 MP2459 Rev. 1.0 3/4/2013 50 80 110 140 400 -40 -10 20 50 80 110 140 26 36 46 56 INPUT VOLTAG ( V ) 2.0 0.5 -40 -10 20 16 750 -40 -10 20 50 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 80 110 140 5 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=12V, VOUT=5V, L=22µH, TA=25°C, unless otherwise noted. Steady State Steady State V IN=8V, OUT I =0.8A Load Transient IOUT =0.15A V IN 5V/di v. V IN 10V/di v. V SW 5V/di v. V SW 10V/di v. V OU T 5V/di v. V OU T 5V/di v. IL 500mA/di v. IL 1A/di v. IOUT =0.2A to 0.7 A V IN 10V/di v. V SW 10V/di v. V OU T 200mV/di v. IL 500mA/di v. Steady State Steady State Load Transient V IN=6V, V I =0.1A OUT =3.3V, OUT V IN=60V, V I =0.9A OUT =3.3V, OUT V OUT =3.3V, OUT I =0.2A to 0.7 A V IN 5V/di v. V IN 50V/di v. V SW 5V/di v. V SW 50V/di v. V OU T 2V/di v. IL 200mA/di v. V OU T 2V/di v. V IN 10V/di v. V SW 10V/di v. V OU T 200mV/di v. IL 500mA/di v. IL 1A/di v. Power Ramp Up Power Ramp Down Short Output V IN=60V, OUT I =0.5A V IN=60V, OUT I =0.5A IOUT =0.65A V IN 50V/di v. V IN 50V/di v. V SW 50V/di v. V SW 50V/di v. V OU T 5V/di v. V OU T 5V/di v. IOU T 500mA/di v. IOU T 500mA/di v. MP2459 Rev. 1.0 3/4/2013 V IN 10V/di v. V SW 10V/di v. V OU T 5V/di v. IL 1A/di v. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 6 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=12V, VOUT=5V, L=22µH, TA=25°C, unless otherwise noted. Enable On Enable Off IOUT =0.5A Short Output Recover IOUT =0.5A IOUT =0.65A V EN 2V/di v. V EN 2V/di v. V IN 10V/di v. V SW 10V/di v. V SW 10V/di v. V SW 10V/di v. V OU T 5V/di v. V OU T 5V/di v. V OU T 5V/di v. IL 500mA/di v. IL 500mA/di v. IL 1A/di v. MP2459 Rev. 1.0 3/4/2013 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 7 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 PIN FUNCTIONS Pin # Name Description 1 BST 2 GND 3 FB 4 EN 5 IN 6 SW MP2459 Rev. 1.0 3/4/2013 Bootstrap. Connect a capacitor between the SW and BS pins to form a floating supply across the power switch driver. This capacitor drives the power switch’s gate above the supply voltage. Ground. Voltage reference for the regulated output voltage. Requires special layout considerations. Isolate this node from the D1 to C1 ground path to prevent switching current spikes from inducing. Feedback. Sets the output voltage. Connect to the tap of an external resistor divider from the output to GND. The frequency foldback comparator lowers the oscillator frequency when the FB voltage is below 250mV to prevent current-limit runaway during a short-circuit fault. On/Off. Pull EN above 1.2V to turn the device ON. For automatic enable, connect to VIN using a 100kΩ resistor. Supply Voltage. The MP2459 operates from a 4.5V-to-55V unregulated input. Requires C1 to prevent large voltage spikes from appearing at the input. Switch Output. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 8 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 OPERATION The MP2459 is a current mode buck regulator. That is, the EA output voltage is proportional to the peak inductor current. At the beginning of a cycle, M1 is off. The EA output voltage is higher than the current sense amplifier output, and the current comparator’s output is low. The rising edge of the 480kHz CLK signal sets the RS Flip-Flop. Its output turns on M1 thus connecting the SW pin and inductor to the input supply. The increasing inductor current is sensed and amplified by the Current Sense Amplifier. Ramp compensation is summed to the Current Sense Amplifier output and compared to the Error Amplifier output by the PWM Comparator. When the sum of the Current Sense Amplifier output and the Slope Compensation signal exceeds the EA output voltage, the RS FlipFlop is reset and M1 is turned off. The external Schottky rectifier diode (D1) conducts the inductor current. If the sum of the Current Sense Amplifier output and the Slope Compensation signal does not exceed the EA output for a whole cycle, then the falling edge of the CLK resets the Flip-Flop. The output of the Error Amplifier integrates the voltage difference between the feedback and the 0.81V bandgap reference. The polarity is such that lower than 0.81V FB pin voltage increases the EA output voltage. Since the EA output voltage is proportional to the peak inductor current, an increase in its voltage also increases current delivered to the output. Figure 1: Functional Block Diagram MP2459 Rev. 1.0 3/4/2013 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 9 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 APPLICATION INFORMATION Setting Output Voltage The external resistor divider sets the output voltage (see the Typical Application schematic). Table 1 lists resistors for common output voltages. The feedback resistor (R1) also sets the feedback loop bandwidth with the internal compensation capacitor (see Figure 1). R2 is: R2 = R1 VOUT −1 0.81V Table 1: Resistor Selection for Common Output Voltages VOUT (V) R1 (kΩ) R2 (kΩ) 1.8 80.6 (1%) 64.9 (1%) 2.5 3.3 5 49.9 (1%) 49.9 (1%) 49.9 (1%) 23.7 (1%) 16.2 (1%) 9.53 (1%) Selecting the Inductor Use an inductor with a DC current rating at least 25% percent higher than the maximum load current for most applications. For best efficiency, the inductor’s DC resistance should be less than 200mΩ. Refer to Table 2 for suggested surface-mount inductors. For most designs, the required inductance value can be derived from the following equation. L= VOUT × ( VIN − VOUT ) VIN × ∆IL × f SW Where ∆IL is the inductor ripple current. Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. The input capacitor impedance at the switching frequency should be less than the input source impedance to prevent high-frequency-switching current from passing through the input. Use ceramic capacitors with X5R or X7R dielectrics for their low ESRs and small temperature coefficients. For most applications, a 4.7µF capacitor will sufficient. Selecting the Output Capacitor The output capacitor keeps the output voltage ripple small and ensures feedback loop stability. The output capacitor impedance should be low at the switching frequency. Use ceramic capacitors with X5R or X7R dielectrics for their low ESR characteristics. For most applications, a 22µF ceramic capacitor will sufficient. PCB Layout Guide PCB layout is very important to stability. Please follow these guidelines and use Figure 2 as reference. 1) Keep the path of switching current short and minimize the loop area formed by the input capacitor, high-side MOSFET, and Schottky diode. 2) Keep the connection from the power ground→Schottky diode→SW pin as short and wide as possible. 3) Ensure all feedback connections are short and direct. Place the feedback resistors and compensation components as close to the chip as possible. 4) Route SW away from sensitive analog areas such as FB. 5) Connect IN, SW, and especially GND to large copper areas to cool the chip for improved thermal performance and longterm reliability. For single layer PCBs, avoid soldering the exposed pad Choose the inductor ripple current to be 30% of the maximum load current. The maximum inductor peak current is: IL(MAX ) = ILOAD + ∆IL 2 Under light-load conditions (below 100mA), use a larger inductance to improve efficiency. . MP2459 Rev. 1.0 3/4/2013 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 10 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 R2 R1 SGND C3 1 BST SW 6 EN 4 2 GND IN 5 3 FB L1 External Bootstrap Diode An external bootstrap diode may enhance regulator efficiency under the following conditions: VOUT=5V or 3.3V; and High duty cycle: D= VOUT >65% VIN R3 In these cases, add an external BST diode from the output of the voltage regulator to the BST pin, as shown in Figure 3. C1 D1 C2 MP2459 PGND Figure 2: PCB Layout Figure 3: Optional Bootstrap Diode for Enhanced Efficiency The recommended external BST diode is IN4148, and the BST capacitor is 0.1µF-1µF. MP2459 Rev. 1.0 3/4/2013 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 11 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 TYPICAL APPLICATION CIRCUIT U1 VIN 5 BS T IN 1 R6 0 MP2459 GND D2 NS SW 6 FB1 0805 C3 100nF 3.3V/0.5 A VOU T D1 DFLS160 EN 4 EN GND FB 3 GND 2 MP2459 Rev. 1.0 3/4/2013 R3 C6 NS NS www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 12 MP2459 – 0.5A, 55V, 480kHz, STEP-DOWN CONVERTER IN A TSOT23-6 PACKAGE INFORMATION TSOT23-6 0.95 B SC 0.60 TYP 2.80 3.00 6 4 1.20 TYP See N ote 7 EXA M PLE TO P M A RK PIN 1 AAAA 1 1.50 1.70 2.60 3.00 2.60 TYP 3 TO P VIEW R EC O MM EN D ED LAN D PA TTER N 0.84 0.90 1.00 M A X 0.09 0.20 SE A TING PLA NE 0.30 0.50 0.95 B SC 0.00 0.10 SEE D ETA IL "A" FR O N T VIEW SID E VIEW N O TE: G A U G E PLA N E 0.25 B SC 0o-8o 0.30 0.50 1)A LL D IM EN SIO N S A R E IN M ILLIM ETERS. 2)PA C KA G E LEN G TH D O ES N O T IN C LU D E M O LD FLA SH, PR O TRU SIO N O R G A TE BUR R. 3)PA C KA G E W ID TH D O ES N O T INC LU D E INTER LEA D FLA SH O R PR O TR U SIO N. 4)LEA D CO PLA NA RITY (B O TTO M O F LEA D S A FTER FO R M IN G ) SH A LL BE 0.10 M ILLIM ETER S M A X. 5)DR A W IN G CO N FO R M S TO JED EC M O-193,VA R IA TIO N A B. 6)DR A W IN G IS NO T TO SC A LE. 7)PIN 1 IS LO WE R LEFT PIN W H EN REA DIN G TO P M A R K FR O M LEFT TO R IG HT,(SE E EX A M PLE TO P M A R K) NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP2459 Rev. 1.0 3/4/2013 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 13